Students will learn about gears through hands on exploration with LEGOs and a worksheet.

Lesson Objectives:

– Familiarize students with gears.

– Learn how gears can be useful.

Materials Needed:

One Homemade LEGO kits for each group:

– Kit should contain several gears of each size (about 5 of each).

– Kit should contain many axles (10 – 20) and bushings (20 – 30).

– Kit should contain a “challenge wall” – This wall should be a collection of beams with holes about 4 inches tall and 6 – 8 inches wide. On the top left corner attach a gear with an axle and a bushing.

– One activity worksheet per student.

Preparation and Set Up:

– Create homemade LEGO kit.

– Make photocopies of worksheets.

– Arrange students in pairs.

– Distribute materials.

Necessary Background

The engineering design process is an eight step process that engineers use to design:

Step 1. Identify the need/problem

Step 2. Research the need/problem

Step 3. Develop possible solutions

Step 4. Select the best possible solution

Step 5. Construct a prototype

Step 6. Test and evaluate the solution(s)

Step 7. Communicate the solution(s)

Step 8. Redesign

Vocabulary:

– Gears

– Drive Gear

– Follower Gear

– Gear Ratio

– Gear Trains

– Simple Machines

Procedure

Explain gears to the class

Talk about how gears are simple machines – a device that helps people do work

Talk about how gears connect to each other with interlocking teeth.

Show that different sized gears have a different number of teeth – This means that one turn of a big gear will turn a small gear more than one turn.

Explain what a gear ratio is. A gear ratio is the number of teeth on the drive gear compared to the number of teeth on the follower gear. Teeth on drive gear: Teeth on follower gear

Explain the difference between gearing up and gearing down and their purpose:

Gearing up mean that for ever revolution of the drive gear the follower gear turns more than one revolution – this is used to make something move faster and gives less power to whatever is attached to the follower gear.

Gearing down means that for every revolution of the drive gear, the follower gear turns less than one revolution – this is used to give more power to whatever is attached to the follower gear because it moves slower with the same power as the drive gear.

Explain that gears are used to slow down or speed up motors in cars, give bikes more resistance up hills, make watch hands move at different speeds etc.

Pass out the gears to the students so they can have a close look.

Have students count the number of teeth on each sized gear.

Have students do the Gear Ratio Worksheet and activity (attached).

Explain to students how when one gear is turned clockwise, the other gear turns counterclockwise.

Pass out the ‘Gears Worksheet’ (attached).

Explain the final challenge of the activity.

Show students the “challenge wall” with one gear at the top left.

Tell students that they must add gears to the wall so that when you turn a driver at the bottom right, the top left gear will turn.

Extensions or Modifications:

– Have students make the top left gear turn clockwise when the bottom right gear is turned counterclockwise.

– Add a spindle attached to a net over a LEGO man on the top left gear that the students have to turn with the other gears. Have the challenge be to free the LEGO man by adding a Gear Train to the lower right of the wall so that when it is turned the net is lifted.